A slip-draft embedded control system was designed and developed for an independent developed 2WD(two-wheel drive)electric tractor,to improve the traction efficiency,operation performance and ploughing depth stability ...A slip-draft embedded control system was designed and developed for an independent developed 2WD(two-wheel drive)electric tractor,to improve the traction efficiency,operation performance and ploughing depth stability of the electric tractor.In this system,the battery of electric tractor was innovatively equivalent to the original counterweight of the fuel tractor.And through dynamic analysis of electric tractor during ploughing,the mathematical model of adjusting the center of gravity about draft force and slip rate was established.Then the automatic adjustment of the center of gravity for electric tractor was realized through the adaptive adjustment of battery position.Finally,the system was carried on electric tractor for performance evaluation under different ploughing conditions,the traction efficiency,slip rate and front wheel load of electric tractor were measured and controlled synchronously to make it close to the set range.And the comparative experiments of ploughing operation were carried out under the two modes of adaptive adjustment of center of gravity and fixed center of gravity.The test results showed that,based on the developed control system,the center of gravity of electric tractor can be adjusted in real time according to the complex changes of working conditions.During ploughing operation with adjusting adaptively battery position,the average values of traction efficiency,slip rate,front wheel load and relative error of tillage depth of electric tractor were 64.5%,22.2%,2045.0 N and 2.0%respectively.Which were optimized by 15.0%,29.5%,19.6%and 80.0%respectively,compared with electric tractor with fixed battery position.The slip-draft embedded control system can not only realize the adaptive adjustment of the center of gravity position in the ploughing process of electric tractor,but also improve the traction efficiency and the stability of ploughing depth,which can provide reference for the actual production operation of electric tractor.展开更多
叶面积指数Leaf Area Index(LAI)作为植被生物量指标之一,耕作区LAI不仅能反映作物的长势动态,且与农业生态、作物产量密切相关。本文通过对2001—2017年中国农田区域的MODIS-LAI长时序数据进行重建,利用Mann-Kendall检验、变异系数、...叶面积指数Leaf Area Index(LAI)作为植被生物量指标之一,耕作区LAI不仅能反映作物的长势动态,且与农业生态、作物产量密切相关。本文通过对2001—2017年中国农田区域的MODIS-LAI长时序数据进行重建,利用Mann-Kendall检验、变异系数、重心迁移模型等方法分析了中国耕作区LAI的时空变化特征。结果表明:①中国耕作区LAI在2001—2017年显波动式上升,且与农作物单产相关系数高达0.91;②不同耕作区季节差异显著,夏季>秋季>春季>冬季,夏季平均为1.54,生长季平均为1.13,秋季平均为0.78,春季平均为0.63,冬季平均为0.31;③2001—2012年二熟、三熟区LAI变化平缓,2012年后有上升趋势但未发生明显突变;一熟区2006年之前处于平稳上升状态,2006年之后发生突变上升趋势显著;④研究时段内我国长江以北的耕作区LAI变异程度较为突出,最高达4.12;5农田面积重心经历了先向西南迁移,后再向西北迁移过程,农田生长季LAI重心相对于农田面积重心变幅较大,经历了南北波动式向西部迁移过程,迁移距离分别为82.78 km、90.53 km。展开更多
基金supported by the International cooperation project of Qilu University of Technology(Grant No.QLUTGJHZ2018022).
文摘A slip-draft embedded control system was designed and developed for an independent developed 2WD(two-wheel drive)electric tractor,to improve the traction efficiency,operation performance and ploughing depth stability of the electric tractor.In this system,the battery of electric tractor was innovatively equivalent to the original counterweight of the fuel tractor.And through dynamic analysis of electric tractor during ploughing,the mathematical model of adjusting the center of gravity about draft force and slip rate was established.Then the automatic adjustment of the center of gravity for electric tractor was realized through the adaptive adjustment of battery position.Finally,the system was carried on electric tractor for performance evaluation under different ploughing conditions,the traction efficiency,slip rate and front wheel load of electric tractor were measured and controlled synchronously to make it close to the set range.And the comparative experiments of ploughing operation were carried out under the two modes of adaptive adjustment of center of gravity and fixed center of gravity.The test results showed that,based on the developed control system,the center of gravity of electric tractor can be adjusted in real time according to the complex changes of working conditions.During ploughing operation with adjusting adaptively battery position,the average values of traction efficiency,slip rate,front wheel load and relative error of tillage depth of electric tractor were 64.5%,22.2%,2045.0 N and 2.0%respectively.Which were optimized by 15.0%,29.5%,19.6%and 80.0%respectively,compared with electric tractor with fixed battery position.The slip-draft embedded control system can not only realize the adaptive adjustment of the center of gravity position in the ploughing process of electric tractor,but also improve the traction efficiency and the stability of ploughing depth,which can provide reference for the actual production operation of electric tractor.
文摘叶面积指数Leaf Area Index(LAI)作为植被生物量指标之一,耕作区LAI不仅能反映作物的长势动态,且与农业生态、作物产量密切相关。本文通过对2001—2017年中国农田区域的MODIS-LAI长时序数据进行重建,利用Mann-Kendall检验、变异系数、重心迁移模型等方法分析了中国耕作区LAI的时空变化特征。结果表明:①中国耕作区LAI在2001—2017年显波动式上升,且与农作物单产相关系数高达0.91;②不同耕作区季节差异显著,夏季>秋季>春季>冬季,夏季平均为1.54,生长季平均为1.13,秋季平均为0.78,春季平均为0.63,冬季平均为0.31;③2001—2012年二熟、三熟区LAI变化平缓,2012年后有上升趋势但未发生明显突变;一熟区2006年之前处于平稳上升状态,2006年之后发生突变上升趋势显著;④研究时段内我国长江以北的耕作区LAI变异程度较为突出,最高达4.12;5农田面积重心经历了先向西南迁移,后再向西北迁移过程,农田生长季LAI重心相对于农田面积重心变幅较大,经历了南北波动式向西部迁移过程,迁移距离分别为82.78 km、90.53 km。
